1. Technical Field
The present invention relates to a multi-band filter.
2. Description of the Related Technology
In accordance with the development of a wireless communication technology, various types of wireless communication services may be used in a portable digital terminal. An example of these wireless communication services includes global system for mobile communication (GSM) using a frequency band of 890 to 960 MHz, personal communication services (PCS) using a frequency band of 1.8 GHz, world interoperability for microwave access (WiMAX) using a frequency band of 3.6 to 3.8 GHz, wireless local area network (WLAN) using a frequency band of 2.4 GHz or 5 GHz, wireless broadband Internet (WiBro) using a frequency band of 2.3 GHz, and Bluetooth using a frequency band of 2.4 GHz, and the like.
Recently, the portable digital terminal uses a multi-band antenna system in order to use wireless communication services provided in various frequency bands. In the multi-band antenna system, a resonator for implementing both of narrow band characteristics and excellent rejection characteristics is required. Korean Patent Laid-Open Publication No. 2008-0056545 relates to the above technology.